Glia Maturation Factor (GMF) is a protein which was discovered, characterized and isolated in our laboratory. The protein can be obtained in highly purified form from bovine brains. GMF not only promotes the phenotypic expression (both chemical and morphological) of normal glioblasts, but also restores contact inhibition in glial tumor cells. The current proposal addresses the question as to whether the effect on glial tumors is accompied by chemical maturation. The glioma cell line 354A will be cloned and investigated for its response to GMF with respect to the following chemical parameters: cyclic AMP, adenylate cyclase, cyclic AMP phosphodiesterase, the neuroectodermal marker S-100 protein, the astrocytic markers glial fibrillary acidic (GFA) protein and glutamine synthetase, the oligodendroglial markers 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) and glycerophosphate dehydrogenase (EC 1.1.1.8)(GPDH). The influence of GMF on the induction of glutamine synthetase and GPDH by hydrocortisone will be investigated. The proposed research is relevant to the understanding of brain tumors and cancer cells in general.